#include <stdio.h>

int main() {
    int n;
    printf("n: ");
    scanf("%d", &n);

    if (n <= 0) {
        printf("\n");
        return 1;
    }

    // ?????,????????????
    int cows[n + 1];
    cows[0] = 1; // ?????????

    for (int i = 1; i <= n; i++) {
        if (i >= 4) {
            // ?i?????????????????????????????
            cows[i] = cows[i - 1] + cows[i - 3];
        } else {
            // ???????????
            cows[i] = cows[i - 1];
        }
    }

    printf("%d,%d\n", n, cows[n]);
    return 0;
}
